[Feature Request] Add i18n/localization support for CLI interface

Problem Description

Claude Code CLI currently displays all interface text in English only, including:

• /help command descriptions
• /context reports
• Command auto-completion hints
• Error/status messages

The existing language setting in settings.json only affects AI conversation responses, not the CLI interface itself.

Current Behavior

// settings.json
{
  "language": "chinese"  // Only affects AI replies, not CLI UI
}

Users who are not fluent in English face a barrier when navigating the CLI interface.

Proposed Solution

Add internationalization (i18n) support to the CLI:

1. Extract UI strings into external locale files (e.g., en.json, zh-CN.json, ja.json)
2. Add a locale or uiLanguage setting in settings.json
3. Allow community contributions for translations

Use Case

Many developers worldwide use Claude Code but may not be native English speakers. Having localized interface text would:

• Improve accessibility for non-English users
• Reduce the learning curve for new users
• Align with the global reach of Claude as an AI assistant

Additional Context

• The claude.exe is compiled as a single executable (~244MB)
• UI strings appear to be hardcoded rather than externalized
• Similar tools like VS Code have robust localization support

Workaround

Currently, users must rely on AI assistance to translate/explain unfamiliar interface text.

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Thank you for considering this feature!